>>It would appear that the behaviour of m_copy()/m_copym() is changed,
>>depending on whether or not M_EXT is set. If M_EXT is set, then the
> I believe the above is the normal behavior, and this has been there
> for a very long time. See TCP/IP Illustrated volume 2, section 2.9.
> To handle, for example, IPsec ESP header (which requires total
> modification of the packet), we reimplement mbuf chain copying,
> without cluster sharing, in few places.
In fact, there are only very few places we would need a deep copy.
IPsec ESP handler processing is the only one item I can imagine.
(do any of drivers need a deep copy? I believe not)
itojun